The present invention relates to a recycling system for a liquid, water-based machine coolant in which the coolant is recycled by various skimming, filtration, and/or centrifuge steps to remove contaminants from the machine coolant such as undesired oils, emulsifiers and/or particulate matter.
Machine coolant recycling systems have been used in the past to recycle liquid, water-based machine coolants used to cool various machines contained in a manufacturing plant or a large machine shop, for example. Typically, a machine in a manufacturing plant has a dedicated coolant recirculating system in which coolant is continuously supplied from a tank, used to cool the machine, and returned to the tank. The machine coolant in the tank is periodically checked, every three weeks for example, to determine whether the coolant requires recycling or disposal.
During normal use, water-based machine coolants become contaminated with various substances due to their contact with the internal structure of the machines which they cool. These substances include particulate matter of various sizes, such as minute metal particles or shavings, oils or other similar contaminants, and/or emulsifiers. It is necessary to remove such contaminants from the machine coolant before it can be reused.
If it requires recycling, the machine coolant is removed from the tank, via a portable sump sucker for example, and transferred to a central recycling system which typically services a large number of machines. Various types of central recycling systems have been used to recycle the machine coolant.
In one prior recycling system, the machine coolant was accumulated in a holding tank from various points in a plant. Some of the contaminants which floated on the surface of the coolant were removed by a vertically moving endless belt in a relatively inefficient manner. The machine coolant was then supplied to a centrifuge that was used to remove particulate matter and undesirable emulsifiers that contaminated the coolant.
After being centrifuged, the machine coolant was chemically tested to determine whether its chemical components were in proper proportion. The constituents of one water-based coolant are 91% deionized water, 3% rust inhibitor, and 6% water-soluble oil. If the proportions of the components of the coolant were not within specification, the necessary components were added to the coolant to bring the components back into proper proportion. The coolant was then returned to the machines.